Why is my iphone closing apps?

My iphone 4 has started to go slow closing apps when only been on them a while, getting hot at times, throwing me off things even messages, my device is not even showing up on itunes to try and do a restore and the battery also draining very quickly not due to upgrade for a year! Any advice greatly appreciated as its driving me mad?!

My ipod touch 4g does the same ever since the new ipod touch 5 came out… I guess this is just Apple's way of getting people to buy new ones. Sucks, i know.